Differential gearing



May, 1923. A

M. J. L. TCWLER DIFFERENTIAL GEARING l Filed April 19, 1919 3 Sheets-Sheet 1 mi: I f\ III?" IIIU I Naim 11 May s, 1923.

M. J. L. TowLER DIFFERENTIAL GEARING 3 Sheets-.Sheet 2 Filed April 19, 1919 May 8, i923.

1,454,578. M. J. L. TOWLER 4 DIFFERENTIAL GEARING Filed April 19 1919 3 Sheets-Sheet 3 Patented May 8, 1923.

Unire sr` MAXMrLIAN J. L. rroWLER, or DETROIT, MICHIGAN.

DIFFERENTIAL GEARNG.

Appncati'on nea Aprii 19, 1919. serial No. 291,223.

To all whom t may concern.'

Be it known that I, MAXIMILIAN J. L. TowLER, a citizen of the United States of America', residing at Detroit, in the county of Vayne and vState of Michigan, have invented certain new and useful improvements in Differential Gearing, of which the following is a specification, reference being had therein to the accompanyingdrawings.

r`his invention relates to gearing wherein two driven members are free to rotate independently, one at a greater speed than the other, and power is applied equally to both when rotating at the same speed, and more particularly to what is commonly known as differential gearing for transmitting power tothe driving wheels of amotor vehicle and Y the like, wherein it is desirable that the members or wheels to which power is transmitted for turning the same, may have relative rotative. movement.

VSo'called differential mechanisms as commonly constructed and embodied in motor vehicle constructions, are defective in that the power is applied thereby to the driven member or wheel offering the'lesser -resistance and the member offering the greater resistance may therefore remain stationary while the other is rotated without eecting a forward movement of the vehicle, as when one wheel has little or no traction. yThe object of this invention is to overcome this defect by introducing into gearing of any desired construction for the purpose', the well known principle in mechanics that where two relatively rotative bodiesl are in frictional contact, no amount of force so directed as to be within the limits-of the angle of friction will effect rotation, and in so applying this principle that the preponderance of power 'will be applied to the driven member oering the greater resistance to turning moment. i y

A further object is -to provide a simple, compact, and eflicient yconstruction particularly applicable to motor vehicle construction, and which will effect the application of alarge proportionate percentage ofthe driving torque'to the driven member offering the greater resistance, and to provide certain other new and useful'V features in the construction and arrangement'of parts.

`With the above and other ends in view the invention consists inthe matters hereinafter set forth andmoreparticularly pointed out in thev appended claims, reference being hadl l Fig. 2 is an end elevation of one part of?? thedivided casing shown in Fig. 1 and showing the gearing in elevation therein;

Fig. 3 is a diagrammatic view of one of ,the trains of gears lshown in Fig. 2; Fig. 4 is a sectional detail illustrative offfa"V-V modified form4 of drive for the cage; y

Fig. 5 is a view similar to Fig. l illustrative of a modification in the construction;

Fig. 6 is a'view similar to Fig. 2 and illus-` trating the construction shownin Fig. 5;

Fig. 7 is a diagrammatic illustration -ofva train of gears shown in Fig. 6;- I

Fig. 8 is a sectional detail similar to Fig.

t showing a modified form of drive for-them cage illustrated in Fig. 5;

Fig. 9 is a diagram illustrative of the arrangement of gears shown in Fig. 2sand their operation; and

Fig. 10 is a diagram illustrative of-ithe` basic principle of operation.

In Fig. 9 is diagrammatically illustrated the application of this principle to: an farrangement of gearing for driving twov independently rotatable members andpermitting of rotation'of said members at relatively different speeds, as inthe soi-called differential mechanisms for driving thetraction wheels ofra self-propelled vehicle and the like, where it is desirable to permit one wheel to rotate, faster than the other.. By employing this principle in such gearing, it is possible to so change the leverages of the gears that a preponderanceof the power will be applied tothe driven member offeringv the greater resistance to turning movement,`

as, for instance, when the driven member or gear E (Fig. 9) offers greater resistance to turning than the driven member or gear E; 21S in 11101501' vehicle construction whenzE f is secured to a shaft for transmitting motion t to one traction wheel which is on hard ground and E is secured to another and separate shaft for transmitting motion to the other traction wheel which is on very soft ground.

' In so called differential mechanisms, the means for connecting the driven members (such as E and E) sothat both will be driven and one permittedto turnindependently l of the other, always embodies members rotatable upon their own axes and revoluble about said members, and by so mountingand arranging one or more of these rotatable members as to take advantage of the angle of friction, the leverage of such connecting means may be so shifted as to cause said means to impart a greater turning force to the member driven thereby which oers the geater resistance, than will be applied to the driven memberl having the lesser resistance, and this principle maybe applied to any desired construction embodying one or more rotating members operatively connecting the driven members of the mechanism.-y

As illustrative of 'an embodiment of the invention, a construction is shown in Figs. l and 2 wherein the driven members are gears E -and'E secured upon the adjacent ends of independently rotatable alined shafts F and F', respectively. rlhe means for operativelyconnecting and drivingthese gears and their shafts comprises two trains of gears A, B, AC,'D, and A, B, C, D, said gears being formed withjournals a, b, c, Z and a', b', c, d', respectively. The journals of all of the gears engage bearings in the side walls'G.'H,`of a suitable cage I which is mounted to turn freely upon the shafts F, F, and which cage is rotated by means of a `suitable worm gear J secured between peripheral flanges. on the two halves G H, of the cage by means of bolts K,I which also serve to secure the `halves together, with all of the gears inclosed therein. Any suitable means may be provided for driving the cage,

and in Fig. 4, a bevelring gear 4L is shown as secured 'to 'the periphery of the cage.

The journals of the gears of both trains of gearing are made as large' in diameter as practicable being equal to the diameter of the gears at the roots of their teeth, to give each journal as broad or extendedan angle of friction relative to the pitch diameter of their gears, as possible,`for the purpose to be hereinafter more fully set forth, and the intermediate gears B,C,B, C of the two trains arepreferably offset -radially relative to the gears A, D, A, D, so thatthey are out of engagement with both ofthe driven gears E, E', said intermediate gears of each train being in lmesh with'each other and one gear C, C havinga face which is double that of the other gears vso that it will mesh with the gear D` D of its train which in turn meshes with the driven Ygear E. The other end gears A, A are in mesh'with the driven gear AE so that said driven gears E, E, are operatively connected by the two trains of gearing and motion isv imparted thereto through said trains to drive their shafts, by the turning of the cage I. said trains permitting relative rotation of said gears E, E', and their shafts in the usual manner.

In Figs. 5 and 6, a slight modiication of the construction and arrangement of gearing is shown to permit the concentric arrangement of the trains of gearing l, 2, 3, Ll and l, 2, 3, A', about the driven gears 5, 5 and their shafts 6, 6, the gears of said trains being provided with enlarged journals as before, mounted in bearings in the walls or two parts 7 and 8 forming the cage which is driven by the worm gear 9 as shown in Fig. 5, secured to the cage by bolts 10, or driven by the bevel ringgear 11 as shown in Fig. 8. In this construction the gears 5 and 5 are spaced apart to provide a space for the intermediate gears 2, 3, and `2, 3 of the two trains of gearing. In this construction the case may be of slightly less diameter than in the construction shown in Figs. l and 2, butin the construction Vshown in said Figs. l and 2, the arrangement permits of shortening the case an amountequal to the width of the intermediate gears of each train shown in Figs. 5 and 6.

The operationof the invention as applied `to the illustrative arrangement of gearing as shown in Figs. l and 2, is illustr-ated'in Fig. 9, the driven gears E, E, and ladriving train of gears A, B, C, D, with their enlarged journals a, Z), c, d, being shown .diagrammatically The Vrotatable cage I in which the train of gearing is mounted is also indicated, and the direction of'rotation of said cage is indicated by the arrow c. If the Vresistance to turning movement of the driven gearsE, E is equal, then there.

will of course be no rotative movement of the gears 'ofthe train upon their axes vbut -they willbe revolved as a unit with the cage,

and by their engagement with the driven gears, rotate said gears and their shafts therewith without relative turning movement of the shafts. If, however, the resistance to turning movement of one gear is greater than the other, then relative rotation of said driven gears ispermitted due to their connection through the train of gearing.

Assuming that of the driven gears, the gear E offers the greater resistance to turning movement, and assuming also that instead of the train of gearing being mounted upon enlarged journals, they be mounted to turn free-ly or without journal friction. then the gear Diwill roll around upon vthe gear E', transmitting motion through C. B. A, which will drive the gear E forwardly or in the direction indicated by the arrow 7c. If however, the gears A, B, C, D, are provided with enlarged journals a, ib, c, fl, as shown. the angle of friction of the several journals will change thev leverage of the gear train and a preponderance of the effective power applied to turn said gears E, E will be applied to the gear E.

i The application of power to each gear A, B, C, D, to turn the same is indicated by the dotted arrows m and the load resistance is applied at a. Each gear therefore represents a power lever the length of which is the distance between the points m, n and the fulcrum vof which is the axis of the gear. The fulcrum of this power lever ishowever in effect shifted by the angle lof friction of the journals which is made effective by providing each gear with journals which are as large in -proportionto the diameter ofVV the gears as it is practicable from a manufacturing standpoint, to make them. If these journals could, in a practical construction, be made of such a size that the force applied at m would come within the angle of friction of the journals, the gears would be locked, as no amount of force so directed as to be within the limiting anglev of friction would result in turning the gears but would only increase the frictional contact of the journals with their bearings, and as this bearing friction increases in direct proportion to the load or power applied, the angles of friction of the journals do not change with the varying load or power and therefore, the power leverageof each gear is constant.

Under the assumption that the gear E offers a greater resistance to turning movement than gear E, then a force tending to revolve the casing in the direction of the arrow k, and'the reaction through gear D against gear E', will tend to turn the gears D, C, B, A, which will react upon their journal bearings in the direction and areas 0 indicated by the broken shade lines, and as these gears are turned in the direction indicated by the arrows thereon, the centers of bearing of the gears, which are their lever fulcrums are shifted due to the angle of friction, so as to `produce in effect a series of short and long lever arms which finally deliver to gear E a much less force tending to turn it than is received by gear E. In other words, either of the gears E or E which offers the greater resistance to turning will receive the greater part of the force tending to turn the casing. The number of gears in the train may be more or less, according to the design of the mechanism, but to give a compact, simple and symmetrical mechanism particularly adapted for use in motor vehicle construction, two trains of gearing of four gears each, with the intermediate gears of each train offset radially to shorten the overall length of the device, seems to be the preferable arrangement.

Obviously, the desired result, to-wit, the application of a large proportion of the effective driving power to the driven member or traction wheel offering the greater resistance, may be secured in various forms and arrangements of differential mechanisms by constructing the mechanism connecting the two driven `members thereof in such man- .membeig driven members, gearing connect- .mg said members, comprising .gears supported in the driving memberby journaled portions, the diameters of which: have such arelation to the diameters ofthe pitch cil'- -cles of the last mentioned gearsfthat apreponderance of the power delivered to the driving member will be transferred to the driven member oifering the greater resistance to rotation.

2. In a differential gearing, a driving member, driven members, means connecting said driven members for differential turning movement and for driving said members, said means including'a gear having journaled portions the diameters of which portions have such relation to the pitch diameter of said gear that a preponderance of the power delivered to the driving member will be applied to the driven member offering the .greater resista-nce to rotation.

3. In differential gearing wherein driven' members may be rotated in unison or relative to each other; of gearing operatively connecting said driven members to effect differential motion between said members and in cluding a driving member rotative upon an axis co-incident with the axis of rotation of said driven members and gears connecting said driven members and mounted upon said driving member, said gears being provided with journals mounted in bearings on said drivin g member with their axes parallel with the axis of rotation of said driven members, each journal having a. diameter relative to the pitch diameter of said gears which is such that a preponderance of powerl delivered to the driving member will be applied to the driven member offering the greater resistance to rotation.

4. Differential gearing comprising rotative driven gears, a carrying member rotatable about the axis of the driven gears, a train of gearing for transmitting motion to and from one to the other of said driven gears, comprising four or more meshing gears with one end gear of the train in mesh with one of the driven gears and the other end gea-r of the train in mesh with the other driven gear, journal bearings on the carrying member for all of the gears of the train, and means for turning the carrying member.

5. Differential gearing comprising rotatable driven gears, a carrying member rotatable about the axis of the driven gears, a train of reversible gearing, one end gear of said train being in mesh with one driven soy gear andthe other end gear of the train in mesh with 'the other driven gear, the intermediate gears of the train being offset radi ally t0 clear said `drivenl gears, journal bearings on the carrying member for said gears of the train, and means for turning the ear rying member.

6. Differential gearing comprising alined and independently rotatabledriven shafts, driven gears onl the adjacent endsof said shafts, a carrying member rotatable about the axis Vof said shafts, means for rotating said carrying member, and two trains of reversible spur gears mounted upon said carryother endy gear of each train in mesh with the other driven gear, the intermediate gears of each train being olf-set radially t0 clear the driven gears.

In testimony whereof I aix. my signature in the presence of two witnesses. t MAXIMILIAN J. L. TOVLER. Y llfvitriesses: f

Lewis E. FLANDERS, ANNA M. Donn. 

